Semiconductor light emitting devices including flexible unitary film on aluminum nitride substrate

ABSTRACT

Semiconductor light emitting devices include an aluminum nitride substrate, a light emitting diode on a face of the substrate and flexible silicone film that includes a silicone lens on the face of the substrate. The light emitting diode emits light through the silicone lens.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/951,157,filed Nov. 22, 2010, which itself is a continuation of application Ser.No. 12/031,951, filed Feb. 15, 2008, which is a divisional ofapplication Ser. No. 10/811,598, filed Mar. 29, 2004, assigned to theassignee of the present application, the disclosures of which are herebyincorporated herein by reference in their entirety as if set forth fullyherein.

FIELD OF THE INVENTION

This invention relates to semiconductor light emitting devices andfabricating methods therefor, and more particularly to packaging andpackaging methods for semiconductor light emitting devices.

BACKGROUND OF THE INVENTION

Semiconductor light emitting devices, such as Light Emitting Diodes(LEDs) or laser diodes, are widely used for many applications. As iswell known to those having skill in the art, a semiconductor lightemitting device includes a semiconductor light emitting element havingone or more semiconductor layers that are configured to emit coherentand/or incoherent light upon energization thereof. It is also known thatthe semiconductor light emitting element generally is packaged toprovide external electrical connections, heat sinking, lenses orwaveguides, environmental protection and/or other functions for thesemiconductor light emitting device. Packaging may be provided, at leastin part, by at least partially surrounding the semiconductor lightemitting device with a dome-shaped transparent plastic shell.

For example, it is known to provide a two-piece package for asemiconductor light emitting device wherein the semiconductor lightemitting element is mounted on a substrate of, for example, alumina,aluminum nitride and/or other materials, which include electrical tracesthereon, to provide external connections for the semiconductor lightemitting element. A second substrate, which, for example, may be silverplated copper, is mounted on the first substrate, for example usingglue, surrounding the semiconductor light emitting element. A lens maybe placed on the second substrate over the semiconductor light emittingelement. Light emitting diodes with two-piece packages as describedabove are described in application Ser. No. 10/446,532 to Loh, entitledPower Surface Mount Light Emitting Die Package, filed May 27, 2003, nowU.S. Pat. No. 7,264,378, assigned to the assignee of the presentinvention, the disclosure of which is hereby incorporated herein byreference in its entirety as if set forth fully herein.

It is often desirable to incorporate phosphor into a semiconductor lightemitting device, to enhance the emitted radiation in a particularfrequency band and/or to convert at least some of the radiation toanother frequency band. Phosphors may be included in a semiconductorlight emitting device using many conventional techniques. In onetechnique, phosphor is coated inside and/or outside the plastic shell.In other techniques, phosphor is coated on the semiconductor lightemitting device itself, for example using electrophoretic deposition. Instill other techniques, a drop of a material such as epoxy that containsphosphor therein may be placed inside the plastic shell, on thesemiconductor light emitting device and/or between the device and theshell. This technique may be referred to as a “glob top”. The phosphorcoatings may also incorporate an index matching material and/or aseparate index matching material may be provided. LEDs that employphosphor coatings are described, for example, in U.S. Pat. Nos.6,252,254; 6,069,440; 5,858,278; 5,813,753; 5,277,840; and 5,959,316.

Unfortunately, the packaging for a semiconductor light emitting devicemay be costly and, in some cases, more costly than the semiconductorlight emitting element itself. Moreover, the assembly process also maybe costly, time consuming and/or subject to failures.

SUMMARY OF THE INVENTION

Some embodiments of the present invention provide semiconductor lightemitting devices that include a substrate having a face, a flexible filmthat includes therein an optical element, on the face, and asemiconductor light emitting element between the substrate and theflexible film and configured to emit light through the optical element.In some embodiments, an optical coupling media, such as optical gel, isprovided between the optical element and the semiconductor lightemitting element. In some embodiments, the face includes a cavitytherein, and the semiconductor light emitting element is in the cavity.The flexible film extends onto the face beyond the cavity, and theoptical element overlies the cavity. In some embodiments, an opticalcoupling media is provided in the cavity. Semiconductor light emittingdevices may be assembled, according to various embodiments of thepresent invention, by mounting a semiconductor light emitting element ona substrate face, and attaching a flexible film that includes therein anoptical element to the substrate face such that, in operation, thesemiconductor light emitting element emits lights through the opticalelement. An optical coupling media may be placed between thesemiconductor light emitting element and the optical coupling element.

Many different configurations of optical elements may be providedaccording to various embodiments of the present invention. In someembodiments, the optical element includes (i.e., comprises) a lens. Inother embodiments, the optical element includes a prism. In otherembodiments, the flexible film includes a first face adjacent thesubstrate and a second face remote from the substrate, and the opticalelement includes a first optical element on the first face, and a secondoptical element on the second face, both of which are located such thatthe light emitting element emits light through the first optical elementand the second optical element. In some embodiments, the optical elementincludes phosphor and/or other optical emission enhancing and/orconverting elements. In still other embodiments, the optical elementincludes an optical scattering element. Combinations and subcombinationsof these and/or other optical elements also may be provided. Moreover,an optical coupling media may be provided between the optical elementand the semiconductor light emitting element in any of theseembodiments.

Many configurations of the flexible film also may be provided accordingto various embodiments of the present invention. For example, in someembodiments, at least a portion of the flexible film that overlies thecavity is transparent to the light, and at least a portion of theflexible film that extends onto the face beyond the cavity is opaque tothe light. In other embodiments, at least a portion of the flexible filmthat overlies the cavity includes a first material and at least aportion of the flexible film that extends onto the face beyond thecavity includes a second material. In still other embodiments, thesemiconductor light emitting element includes a wire that extendstowards and contacts the flexible film in the cavity, and the flexiblefilm includes a transparent conductor in the cavity that electricallyconnects to the wire. Combinations and subcombinations of these and/orother configurations of flexible film also may be provided.

In other embodiments, an attachment element also is provided that isconfigured to attach the flexible film and the substrate to one another.Many conventional attachment techniques can be used to provide anattachment element.

Some embodiments of the present invention may be configured toincorporate phosphor into the semiconductor light emitting device. Insome embodiments, phosphor is provided on the flexible film between thelens and the semiconductor light emitting element. In other embodiments,the lens includes a concave inner surface adjacent the semiconductorlight emitting element, and the phosphor includes a conformal phosphorlayer on the concave inner surface. In yet other embodiments, theoptical element includes a lens that overlies the cavity and protrudesaway from the cavity, the flexible film further includes a protrudingelement between the lens and the light emitting element that protrudestowards the cavity, and a conformal phosphor coating is provided on theprotruding element. Combinations and subcombinations of these and/orother configurations of phosphor also may be provided. Moreover, anoptical coupling media may be provided between the phosphor and thesemiconductor light emitting element in any of these embodiments.

In still other embodiments of the present invention, the semiconductorlight emitting element includes a wire that extends towards the flexiblesubstrate. In some of these embodiments, the optical element includes aprism that is configured to reduce shadowing by the wire, of the lightthat is emitted from the semiconductor light emitting element.

Multiple semiconductor light emitting elements and/or optical elementsmay be incorporated in a semiconductor light emitting device accordingto various embodiments of the present invention. Each semiconductorlight emitting element may be included in its own individual cavityand/or multiple semiconductor light emitting elements may be included ina single cavity. Moreover, in some embodiments, the same phosphor may beincluded on the flexible film for each optical element. In otherembodiments, different phosphors may be used. For example, a firstphosphor layer and a first semiconductor light emitting element may beconfigured to generate red light, a second phosphor layer and a secondsemiconductor light emitting element may be configured to generate bluelight, and a third phosphor layer and a third semiconductor lightemitting element may be configured to generate green light. Combinationsand subcombinations of these and/or other multiple semiconductor lightemitting elements and/or multiple optical elements also may be provided.Finally, combinations and subcombinations of these and/or other opticalelements, flexible films, phosphor and/or multiple elements may beprovided, according to various embodiments of the present invention.

Semiconductor light emitting devices according to yet other embodimentsof the present invention include a substrate comprising alumina, a lightemitting diode on a face of the substrate, and a flexible filmcomprising silicone on the face of the substrate and on the lightemitting diode. The flexible film comprising silicone includes therein alens comprising silicone adjacent the light emitting diode, such thatthe light emitting diode emits light through the lens. In otherembodiments, the flexible film comprising silicone is attached to thesubstrate, such that the flexible film comprising silicone conforms tothe light emitting diode as it expands and contracts during operationthereof. Phosphor also may be provided between the lens and the lightemitting diode. Various embodiments of the flexible silicone film, thelens, the phosphor and/or other elements may be provided according toany of the other embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded cross-sectional view of semiconductor lightemitting devices and fabrication methods therefor, according to variousembodiments of the present invention.

FIGS. 2-12 are cross-sectional views of semiconductor light emittingdevices according to various embodiments of the present invention.

FIG. 13 is a perspective view of a semiconductor light emitting deviceaccording to various embodiments of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, the size and relative sizes of layers and regions may beexaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. It will be understood that if part of an element, such as asurface, is referred to as “inner,” it is farther from the outside ofthe device than other parts of the element. Furthermore, relative termssuch as “beneath” or “overlies” may be used herein to describe arelationship of one layer or region to another layer or region relativeto a substrate or base layer as illustrated in the figures.

It will be understood that these terms are intended to encompassdifferent orientations of the device in addition to the orientationdepicted in the figures. Finally, the term “directly” means that thereare no intervening elements. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first region, layer or sectiondiscussed below could be termed a second region, layer or section, and,similarly, a second without departing from the teachings of the presentinvention.

FIG. 1 is an exploded cross-sectional view of semiconductor lightemitting devices and assembling methods therefor, according to variousembodiments of the present invention. Referring to FIG. 1, thesesemiconductor light emitting devices 100 include a substrate 110 havinga face 110 a, a flexible film 120 that includes therein an opticalelement 130, on the face 110 a, and a semiconductor light emittingelement 140 between the substrate 110 and the flexible film 120, andconfigured to emit light 160 through the optical element. An attachmentelement 150 may be used to attach the flexible film 120 and thesubstrate 110 to one another.

Still referring to FIG. 1, the substrate 110 may include alumina,aluminum nitride, metal and/or other materials that are conventionallyused for mounting semiconductor light emitting elements thereon. Inother embodiments, the substrate 110 can be a solid metal block, asdescribed in copending application Ser. No. 10/659,108 to Negley et al.,entitled Solid Metal Block Mounting Substrates for Semiconductor LightEmitting Devices, and Oxidizing Methods for Fabricating Same, filed Sep.9, 2003, now U.S. Pat. No. 7,183,587, assigned to the assignee of thepresent invention, the disclosure of which is hereby incorporated hereinby reference in its entirety as if set forth fully herein. The design ofsubstrates 110 are well known to those having skill in the art and neednot be described further herein.

The semiconductor light emitting element 140 may include a lightemitting diode, laser diode and/or other semiconductor device whichincludes one or more semiconductor layers, which may include silicon,silicon carbide, gallium nitride and/or other semiconductor materials, asubstrate which may include sapphire, silicon, silicon carbide and/orother microelectronic substrates, and one or more contact layers whichmay include metal and/or other conductive layers. In some embodiments,ultraviolet, blue and/or green LEDs may be provided. The design andfabrication of semiconductor light emitting devices 140 are well knownto those having skill in the art and need not be described in detailherein.

For example, the light emitting elements 140 may be galliumnitride-based LEDs or lasers fabricated on a silicon carbide substratesuch as those devices manufactured and sold by Cree, Inc. of Durham,N.C. The present invention may be suitable for use with LEDs and/orlasers as described in U.S. Pat. Nos. 6,201,262; 6,187,606; 6,120,600;5,912,477; 5,739,554; 5,631,190; 5,604,135; 5,523,589; 5,416,342;5,393,993; 5,338,944; 5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or4,918,497, the disclosures of which are incorporated herein by referenceas if set forth fully herein. Other suitable LEDs and/or lasers aredescribed in published U.S. Patent Publication No. US 2003/0006418 A1entitled Group III Nitride Based Light Emitting Diode Structures With aQuantum Well and Superlattice, Group III Nitride Based Quantum WellStructures and Group III Nitride Based Superlattice Structures,published Jan. 9, 2003, as well as published U.S. Patent Publication No.US 2002/0123164 A1 entitled Light Emitting Diodes IncludingModifications for Light Extraction and Manufacturing Methods Therefor.Furthermore, phosphor coated LEDs, such as those described in U.S.application Ser. No. 10/659,241, entitled Phosphor-Coated Light EmittingDiodes Including Tapered Sidewalls and Fabrication Methods Therefor,filed Sep. 9, 2003, now U.S. Pat. No. 6,853,010, the disclosure of whichis incorporated by reference herein as if set forth fully, may also besuitable for use in embodiments of the present invention. The LEDsand/or lasers may be configured to operate such that light emissionoccurs through the substrate. In such embodiments, the substrate may bepatterned so as to enhance light output of the devices as is described,for example, in the above-cited U.S. Patent Publication No. US2002/0123164 A1.

Still referring to FIG. 1, the flexible film 120 can provide a coverslip that can be made of a flexible material such as a conventional RoomTemperature Vulcanizing (RTV) silicone rubber. Other silicone-basedand/or flexible materials may be used. By being made of a flexiblematerial, the flexible film 120 can conform to the substrate 110 as itexpands and contracts during operations. Moreover, the flexible film 120can be made by simple low-cost techniques such as transfer molding,injection molding and/or other conventional techniques that are wellknown to those having skill in the art.

As described above, the flexible film 120 includes therein an opticalelement 130. The optical element can include a lens, a prism, an opticalemission enhancing and/or converting element, such as a phosphor, anoptical scattering element and/or other optical element. One or moreoptical elements 130 also may be provided, as will be described indetail below. Moreover, as shown in FIG. 1, an optical coupling media170, such as an optical coupling gel and/or other index matchingmaterial, may be provided between the optical element 130 and thesemiconductor light emitting device 140, in some embodiments.

Still referring to FIG. 1, the attachment element 150 can be embodied asan adhesive that may be placed around the periphery of the substrate110, around the periphery of the flexible film 120 and/or at selectedportions thereof, such as at the corners thereof. In other embodiments,the substrate 110 may be coined around the flexible film 120, to providean attachment element 150. Other conventional attaching techniques maybe used.

FIG. 1 also illustrates methods of assembling semiconductor lightemitting devices 100 according to various embodiments of the presentinvention. As shown in FIG. 1, a semiconductor light emitting element140 is mounted on a substrate face 110 a. A flexible film 120 thatincludes therein an optical element 130 is attached to the substrateface 110 a, for example using an attachment element 150, such that, inoperation, the semiconductor light emitting element emits light 160through the optical element 130. In some embodiments, an opticalcoupling media 170 is placed between the semiconductor light emittingelement 140 and the optical element 130.

FIG. 2 is a cross-sectional view of semiconductor light emitting devicesaccording to other embodiments of the present invention. In theseembodiments, the substrate face 110 a includes a cavity 110 b therein.The flexible film 120 extends onto the face 110 a beyond the cavity 110b. The optical element 130 overlies the cavity 110 b, and thesemiconductor light emitting element 140 is in the cavity 110 b, and isconfigured to emit light 160 through the optical element 130. In FIG. 2,the optical element 130 includes a concave lens. In some embodiments, anoptical coupling media 170 is provided in the cavity 110 b between theoptical element 130 and the semiconductor light emitting element 140. Insome embodiments, the optical coupling media 170 fills the cavity 110 b.

FIG. 3 is a cross-sectional view of other embodiments of the presentinvention. As shown in FIG. 3, two optical elements 130 and 330 areincluded in the flexible film 120. A first optical element 130 includesa lens and a second optical element 330 includes a prism. Light from thesemiconductor light emitting element 140 passes through the prism 330and through the lens 130. An optical coupling media 170 also may beprovided. In some embodiments, the optical coupling media 170 fills thecavity 110 b. The optical coupling media 170 may have a sufficientdifference in index of refraction difference from the prism such thatthe prism can reduce shadowing. As shown in FIG. 3, the semiconductorlight emitting element includes a wire 140 a that extends towards theflexible film 120, and the prism 330 is configured to reduce shadowingby the wire 140 a of the light that is emitted from the semiconductorlight emitting element 140. More uniform light emissions thereby may beprovided, with reduced shadowing of the wire 140 a. It will beunderstood that the term “wire” is used herein in a generic sense toencompass any electrical connection for the semiconductor light emittingelement 140.

FIG. 4 is a cross-sectional view of other embodiments of the presentinvention. As shown in FIG. 4, phosphor 410 is provided on the flexiblefilm 120 between the lens 130 and the semiconductor light emittingelement 140. The phosphor 410 can include cerium-doped Yttrium AluminumGarnet (YAG) and/or other conventional phosphors. In some embodiments,the phosphor comprises Cesium doped Yttrium Aluminum Garnet (YAG:Ce). Inother embodiments, nano-phosphors may be used. Phosphors are well knownto those having skill in the art and need not be described furtherherein. An optical coupling media 170 also may be provided that may fillthe cavity 110 b.

FIG. 5 illustrates yet other embodiments of the present invention. Inthese embodiments, the lens 130 includes a concave inner surface 130 aadjacent the semiconductor light emitting element 140, and the phosphor410 includes a conformal phosphor layer on the concave inner surface 130a. An optical coupling media 170 also may be provided that may fill thecavity 110 b.

FIG. 6 is a cross-sectional view of other embodiments. As shown in FIG.6, at least a portion 120 d of the flexible film 120 that overlies thecavity 110 b is transparent to the light. Moreover, at least a portion120 c of the flexible film 120 that extends onto the face 110 a beyondthe cavity 110 b is opaque to the light, as shown by the dotted portions120 c of the flexible film 120. The opaque regions 120 c can reduce orprevent bouncing of light rays, and thereby potentially produce a moredesirable light pattern. An optical coupling media 170 also may beprovided that may fill the cavity 110 b.

FIG. 7 is a cross-sectional view of other embodiments of the presentinvention wherein the flexible film 120 may be fabricated of multiplematerials. As shown in FIG. 7, at least a portion 120 d of the flexiblefilm 120 that overlies the cavity 110 b includes a first material, andat least a portion 120 c of the flexible film 120 that extends onto theface 110 a beyond the cavity 110 b includes a second material. Two ormore materials may be used in the flexible film 120 in some embodiments,to provide different characteristics for the portion of the flexiblefilm 120 through which light is emitted and through which light is notemitted. Multiple materials may be used for other purposes in otherembodiments. For example, an inflexible and/or flexible plastic lens maybe attached to a flexible film. Such a flexible film 120 with multiplematerials may be fabricated using conventional multiple moldingtechniques, for example. In some embodiments, the first material that ismolded may not be fully cured, so as to provide a satisfactory bond thatattaches to the second material that is subsequently molded. In otherembodiments, the same material may be used for the optical element andthe flexible film, wherein the optical element is formed and then theflexible film is formed surrounding the optical element. An opticalcoupling media 170 also may be provided that may fill the cavity 110 b.

FIG. 8 is a cross-sectional view of other embodiments of the presentinvention. In these embodiments, the semiconductor light emittingelement 140 includes a wire 140 a, that extends towards and contacts theflexible film 120 in the cavity 110 b. The flexible film 120 includes atransparent conductor 810 which can include Indium Tin Oxide (ITO)and/or other conventional transparent conductors. The transparentconductor 810 extends in the cavity 110 b and electrically connects tothe wire. Reduced shadowing by the contact 140 a thereby may beprovided. Moreover, a wire bond to the substrate 110, and the potentialconsequent light distortion, may be reduced or eliminated. An opticalcoupling media 170 also may be provided that may fill the cavity 110 b.

FIG. 9 is a cross-sectional view of other embodiments of the presentinvention. As shown in FIG. 9, the optical element 130 includes a lensthat overlies the cavity 110 b and protrudes away from the cavity 110 b.The flexible film 120 further includes a protruding element 930 betweenthe lens 130 and the light emitting element 140 that protrudes towardsthe cavity 110 b. As shown in FIG. 9, a conformal phosphor layer 410 isprovided on the protruding element 930. By providing the protrudingelement 930 on the back of the lens 130, optical coupling media 170 inthe device may be displaced. Arrangements of FIG. 9 may thus providemore uniform phosphor coating at desired distances from the lightemitting element 140, so as to provide more uniform illumination. Theoptical coupling media 170 may fill the cavity 110 b.

FIGS. 10 and 11 illustrate semiconductor light emitting devicesincluding multiple semiconductor light emitting elements and/or multipleoptical elements according to various embodiments of the presentinvention. For example, as shown in FIG. 10, the optical element 130 isa first optical element, and the semiconductor light emitting element140 is a first semiconductor light emitting element. The flexible film120 also includes therein a second optical element 130′ that is spacedapart from the first optical element 130, and the device furtherincludes a second semiconductor light emitting element 140′ between thesubstrate 110 and the flexible film 120, and configured to emit lightthrough the second optical element 130′. Moreover, a third opticalelement 130″ and a third semiconductor light emitting element 140″ alsomay be provided. The optical elements 130, 130′ and 130″ may be the sameand/or different from one another, and the semiconductor light emittingelements 140, 140′ and 140″ may be the same and/or different from oneanother. Moreover, in embodiments of FIG. 10, the cavity 110 b is afirst cavity, and second and third cavities 110 b′, 110 b″,respectively, are provided for the second and third semiconductor lightemitting elements 140′, 140″, respectively. The cavities 110 b, 110 b′and 110 b″ may be the same and/or may have different configurations fromone another. An optical coupling media 170 also may be provided that mayfill the cavity or cavities.

As also shown in FIG. 10, the phosphor 410 may be a first phosphorlayer, and second and/or third phosphor layers 410′ and 410″,respectively, may be provided on the flexible film 120 between thesecond optical element 130′ and the second semiconductor light emittingelement 140′, and between the third optical element 130″ and the thirdsemiconductor light emitting element 140″, respectively. The phosphorlayers 410, 410′, 410″ may be the same, may be different and/or may beeliminated. In particular, in some embodiments of the present invention,the first phosphor layer 410 and the first semiconductor light emittingelement 140 are configured to generate red light, the second phosphorlayer 410′ and the second semiconductor light emitting element 140′ areconfigured to generate blue light, and the third phosphor layer 410″ andthe third semiconductor light emitting element 140″ are configured togenerate green light. A Red, Green, Blue (RGB) light emitting elementthat can emit white light thereby may be provided in some embodiments.

FIG. 11 is a cross-sectional view of other embodiments of the presentinvention. In these embodiments, a single cavity 1100 is provided forthe first, second and third semiconductor light emitting elements 140,140′ and 140″, respectively. An optical coupling media 170 also may beprovided that may fill the cavity 1100.

FIG. 12 is a cross-sectional view of yet other embodiments of thepresent invention. In FIG. 12, the optical element 1230 comprises a lenshaving phosphor dispersed therein. Lenses including phosphor dispersedtherein are described, for example, in application Ser. No. 10/659,240to Negley et al., entitled Transmissive Optical Elements IncludingTransparent Plastic Shell Having a Phosphor Dispersed Therein, andMethods of Fabricating Same, filed Sep. 9, 2003, now U.S. Pat. No.7,029,935, assigned to the assignee of the present invention, thedisclosure of which is hereby incorporated herein by reference in itsentirety as if set forth fully herein. An optical coupling media 170also may be provided that may fill the cavity 110 b.

In still other embodiments of the present invention, an opticalscattering element may be embedded in the lens as shown in FIG. 12,and/or provided as a separating layer as shown, for example, in FIG. 9,in addition or instead of phosphor.

FIG. 13 is a perspective view of semiconductor light emitting devicesaccording to other embodiments of the present invention. The substrate110 is attached to a conventional package 1310. An optical couplingmedia 170 also may be provided.

It will be understood by those having skill in the art that variousembodiments of the invention have been described individually inconnection with FIGS. 1-13. However, combinations and subcombinations ofthe embodiments of FIGS. 1-13 may be provided according to variousembodiments of the present invention.

Additional discussion of various embodiments of the present inventionnow will be provided. In particular, in some embodiments, the flexiblefilm 120 that was described above may be made of a flexible materialsuch as RTV, GE RTV 615 marketed by GE, UR 234 marketed byThermoset/Lord Corp. and/or other conventional flexible materials, andin some embodiment may be between about 25 μm and about 500 μm thick.The flexible film 120 incorporates one or more optical elements 130 toachieve a desired optical design. Being made of a flexible material, theflexible film 120 can conform to the semiconductor light emitting deviceas it expands and contracts. Moreover, in some embodiments, the flexiblefilm can be fabricated by simple low cost techniques such as transfermolding, injection molding and/or other techniques, and may includemultiple optical elements and/or other features on either side of theflexible film membrane. This may permit a “single” placement of acomplex optical element upon a package (or substrate to a package) thatcan include multiple LED emitters.

Conventionally, LED packages use a lens molded from rigid plastic orglass. Either a hard encapsulant is used to encapsulate the chip andform the optical element, or a lens is applied upon an optical couplingmedia, such as an optical gel, for example Nye optical gel. The hardencapsulant may be plagued by optical degradation and high stress on LEDchips, and power LED chips in particular, and the optical coupling mediamay also potentially create problems because this gel may be exposed onthe surface of the part which may result in trapping of dust/debris onthe exposed material due to the stickiness of the gel. In contrast,flexible films 120 according to some embodiments of the presentinvention can be the terminating surface of the package using an opticalcoupling media 170, and also includes the optical elements 130, such asone or more optical lens. The ability to place one unit (the flexiblefilm with multiple optical elements) can potentially provide a benefitwhen using a package that has multiple LEDs in it. Instead of placing alens for each LED, the single placement of a flexible film 130 can beprovided.

Still other features can be incorporated into the flexible film 130. Forexample, on the opposing side of the optical lens, a filled regionincluding a phosphor and/or an optical coupling media 170 may beincorporated to give the features of a paint-on lens for making whitelight. A paint-on lens for making white light is described inapplication Ser. No. 10/666,399 to Michael Leung, entitled Molded ChipFabrication Method and Apparatus, filed Sep. 18, 2003, now U.S. PatentApplication Publication 2005/0062140, assigned to the assignee of thepresent invention, the disclosure of which is hereby incorporated hereinby reference in its entirety as if set forth fully herein.

Some embodiments of the present invention can reduce or minimize thevolume of optical coupling media 170, by providing a protrusion such aswas described, for example, in FIG. 9. By reducing the amount of opticalcoupling media 170, a more uniform light emission may be provided. Thus,these and/or other embodiments of the present invention can reduce oreliminate angular-dependent radiation patterns of light output from thelight emitting device, such as angular dependence of Color CorrelatedTemperature (CCT). Thus, light intensity and the x, y chromaticityvalues/coordinates from all surfaces of the device can remain relativelyconstant in some embodiments. This may be advantageous when used forillumination applications, such as in a room, where a spotlight effectis not desirable.

In the drawings and specification, there have been disclosed embodimentsof the invention and, although specific terms are employed, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being set forth in the followingclaims.

1. A semiconductor light emitting device comprising: a solid aluminumnitride block; a light emitting diode on a face of the solid aluminumnitride block; and a flexible unitary film comprising silicone thatextends conformally on the face of the solid aluminum nitride blockoutside the light emitting diode and that also extends on the lightemitting diode, the flexible unitary film comprising silicone includingtherein a lens comprising silicone adjacent the light emitting diode,such that the light emitting diode emits light through the lens.
 2. Asemiconductor light emitting device according to claim 1 wherein theflexible unitary film comprising silicone is attached to the solidaluminum nitride block such that the flexible unitary film comprisingsilicone conforms to the light emitting diode as it expands andcontracts during operation thereof.
 3. A device according to claim 2further comprising phosphor between the lens and the light emittingdiode.
 4. A device according to claim 3 wherein the lens includes aconcave inner surface adjacent the light emitting diode and wherein thephosphor comprises a conformal phosphor layer on the concave innersurface.
 5. A device according to claim 3 further comprising an opticalcoupling media between the phosphor and the light emitting diode.
 6. Adevice according to claim 2 further comprising an attachment elementthat is configured to attach the flexible unitary film and the solidaluminum nitride block to one another such that the flexible unitaryfilm comprising silicone conforms to the light emitting diode as itexpands and contracts during operation thereof.
 7. A semiconductor lightemitting device comprising: a substrate comprising aluminum nitride; alight emitting diode on a face of the substrate; and a flexible filmcomprising silicone that extends conformally onto the face of thesubstrate beyond the light emitting diode and that also extends on thelight emitting diode, the flexible film comprising silicone includingtherein a lens comprising silicone adjacent the light emitting diode,such that the light emitting diode emits light through the lens; whereinat least a portion of the flexible film comprising silicone thatoverlies the light emitting diode is transparent to the light andwherein at least a portion of the flexible film comprising silicone thatextends conformally onto the face beyond the light emitting diode isopaque to the light.
 8. A semiconductor light emitting device accordingto claim 7 wherein the flexible film comprising silicone is attached tothe substrate such that the flexible film comprising silicone conformsto the light emitting diode as it expands and contracts during operationthereof.
 9. A device according to claim 8 further comprising phosphorbetween the lens and the light emitting diode.
 10. A device according toclaim 9 wherein the lens includes a concave inner surface adjacent thelight emitting diode and wherein the phosphor comprises a conformalphosphor layer on the concave inner surface.
 11. A device according toclaim 9 further comprising an optical coupling media between thephosphor and the light emitting diode.
 12. A device according to claim 8further comprising an attachment element that is configured to attachthe flexible film and the substrate to one another such that theflexible film comprising silicone conforms to the light emitting diodeas it expands and contracts during operation thereof.
 13. Asemiconductor light emitting device comprising: a substrate comprisingaluminum nitride; a light emitting diode on a face of the substrate; anda flexible film comprising silicone that extends conformally onto theface of the substrate beyond the light emitting diode and that alsoextends on the light emitting diode, the flexible film comprisingsilicone including therein a lens comprising silicone adjacent the lightemitting diode, such that the light emitting diode emits light throughthe lens; wherein at least a portion of the flexible film comprisingsilicone that overlies the light emitting diode comprises a firstmaterial and wherein at least a portion of the flexible film comprisingsilicone that extends conformally onto the face beyond the lightemitting diode comprises a second material that is different from thefirst material.
 14. A semiconductor light emitting device according toclaim 13 wherein the flexible film comprising silicone is attached tothe substrate such that the flexible film comprising silicone conformsto the light emitting diode as it expands and contracts during operationthereof.
 15. A device according to claim 14 further comprising phosphorbetween the lens and the light emitting diode.
 16. A device according toclaim 15 wherein the lens includes a concave inner surface adjacent thelight emitting diode and wherein the phosphor comprises a conformalphosphor layer on the concave inner surface.
 17. A device according toclaim 15 further comprising an optical coupling media between thephosphor and the light emitting diode.
 18. A device according to claim14 further comprising an attachment element that is configured to attachthe flexible film and the substrate to one another such that theflexible film comprising silicone conforms to the light emitting diodeas it expands and contracts during operation thereof.